Substring help

Hello to all... this is my first post on the forum, and I'm sure I'll stick around for extra help :)

Anyways. I'm practicing on CodingBat.com and got stuck on this task: CodingBat Java String-1 nTwice

Here's my code:

Code Java:

---

public String nTwice(String str, int n) 
{
  String a = str.substring(0,n);
  String b = str.substring();
  String c = a+b;
  return c;
}

---

I THINK that my method will work, but I am unsure about how to define String b so that the program does what it is intended to do. What should go between the parentheses?

Read the API for String , more specifically the length method.

Have a look at one of the substring methods. There is one with 1 parameter instead of two.

This method will get the String:
Starting from the the parameter index value AND
Getting the rest of the String.

So, while this method:

Code java:

---

String test = "test";
String sub = test.substring(0,2);

---

will set sub to be te,
This method:

Code java:

---

String test = "test";
String sub = test.substring(1);

---

will set sub to be est.

Does that make sense?